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Practice makes perfect

How sight "builds" the brain during development. The reasearch published in Nature Communications

Scientists have discovered the protagonists of the development of the visual cortex in the brain during postnatal growth: small molecules called microRNAs, or miR, allow the maturation of brain circuits and, in turn, increase in number the more "seeing" we do. This is the result of an international study coordinated by Thomas Pizzorusso, professor of Psychobiology and Physiological Psychology at the University of Florence, whose results have been published by the journal Nature Communications ("Mir-132/212 is required for maturation of binocular matching of orientation preference and depth perception "doi: 10.1038 / ncomms15488).

The research - developed with the contribution of young PhD students of the Scuola Normale Superiore in Pisa and the Tuscan Pegaso regional doctorate programme, in collaboration with the University of California at Irvine, the National Research Council, Institute of Neuroscience in Pisa and the BIO @ SNS Laboratory of the Scuola Normale in Pisa - has identified a class of small molecules, microRNAs, which could be responsible for the processes of maturation and remodelling of brain circuits during postnatal development. Such molecules are regulators of the process through which the information contained in a gene is converted into a functional macromolecule. "By studying the development of the visual cortex, said Pizzorusso, who led a team of researchers from the Department of Neurosciences, Psychology, Drug Research and Child Health of the University of Florence, we have shown that some microRNAs increase tremendously in the visual cortex during the functional maturation period." It is a virtuous circle.

By studying in more detail the role of one of these molecules, the miR-132, scholars have found that increasing its amount during development allows the functional maturation of "excitatory" neurons, those that transmit visual information while, in its absence, 3D vision does not develop. The researchers then observed that it is the visual stimulation itself that results in the increase of miR-132, as in a virtuous circle where this micromolecule allows visual development and visual experience facilitates the increase of miR-132 and therefore brain development.

These findings provide new research horizons on neurodevelopment disiease and the elderly. "The results of this research - Pizzorusso comments - offer useful elements in the study of psychiatric illnesses such as schizophrenia, or in the study of cerebral function disorders such as autism, which often show alterations in mechanisms through which experience regulates gene expression during development. The study also identifies genes controlled by the miR-132 providing new candidates for further research into the genetic causes of neurodevelopmental diseases. But there is another interesting aspect of the research, concludes Pizzorusso. The molecular factors that mediate experience activities in the brain are involved in important cognitive functions, such as learning, which are also present in adults and the elderly. For example, miR-132 is also the microRNA which is most reduced in the brain of patients with Alzheimer's disease: in this case the lack of a mediator in the action of external stimuli on the brain could help to determine the cognitive defects typical of dementia. "